Lesson on Multiplicity

One concept in relationships is what is called Multiplicity. It shows the number of objects that can participate in a relationship.

To illustrate, here are some examples:

Relationship	Example
One To One	One class occupies one classroom
One To Many	One teacher teaches many classes
Many To Many	One teacher teaches many students. One student learns from many teacher. So in short, it's 2 One To Many relationships combined.